Production of alkyl aryl compounds



atent @ce 3,071,629 Patented Jan. 1, 1963 PRGDUCTIUN F ALKYL ARYL COMPOUNDS Peter Thomas White and Frederick William Bertram Porter, Sunhury-on-Thames, England, assignors to The British Petroleum (Iompany Limited, London, England,

a joint-stock corporation of Great Britain No Drawing. Filed Dec. 1, 1959, Ser. No. 856,343 Claims priority, application Great Britain Dec. 3, 1958 2 Claims. (Cl. 260-668) This invention relates to the production of alkyl aryl compounds and in particular to the production of such compounds suitable for use in the production of detergents and wetting agents which comprise salts of sulphonated alkyl aryl compounds.

It is well known that alkyl aryl compounds suitable for the production of such sulphonates may be produced by the treatment of aryl hydrocarbons with olefinic hydrocarbons having from 8 to 20 carbon atoms per molecule. Such processes involve the preparation of a suitable olefinic hydrocarbon and the treatment of an aryl hydrocarbon therewith.

In accordance with the present invention, alkyl aryl hydrocarbons are produced by a process which comprises contacting alkyl naphthenes having from 14 to 26 carbon atoms per molecule with a dehydrogenation catalyst at a temperature of from 370 C. to 580 C.

The feedstock need not consist entirely of alkyl naphthenes, and may contain for example a minor proportion of paraffinic and/ or olefinic hydrocarbons. A particularly preferred feedstock is the rafiinate Obtained by the solvent extraction of a cycle oil, and the present invention includes a process for the production of alkyl aryl hydrocarbons comprising subjecting a cycle oil to seiective solvent extraction, and contacting the rafiinate with a dehydrogenation catalyst at a temperature of from 370 C. to 580 C.

During the catalytic cracking of hydrocarbon oils, whether gas oils or oils boiling above that range e.g. wax distillate fractions, it is customary to fractionate the catalytically cracked products so as to give a heavy gas oil fraction boiling above 275 C. which together with the fractionator bottoms, if desired, may be recycled to the cat. cracker. This so-called cycle oil is not normally recycled to destruction, however, and in consequence appreciable quantities of the oil may be available, for which the normal outlet would be fuel oil.

The dehydrogenation catalyst may be one or more group VI or group VIII metals or their oxides or sulphides on a support, for example, alumina, or silica-alumina. Preferred metals are chromium, molybdenum, cobalt, nickel, palladium or platinum and particular examples of suitable catalysts are molybdenum oxide on alumina (preferably to 25% Wt. molybdenum oxide expressed as M00 cobalt and molybdenum oxides on alumina (preferably l to 5% wt. cobalt oxide expressed as C00, and 5 to 25% wt. molybdenum oxide expressed as M00 nickel on alumina (preferably 5 to 15% wt. nickel ex pressed as elemental nickel), and platinum on alumina (preferably 0.1 to 5% wt. platinum expressed as elemental platinum). A particularly effective catalyst is one consisting essentially of chromium oxide supported on alumina. This catalyst may contain a minor proportion of one or more promoters, for example a rare earth or mixture of rare earths, bismuth, boron, germanium, manganese, iron, beryllium or nickel, preferably in combination with an alkali metal such as potassium. Another particularly effective promoter is a minor proportion of a spinel, for example cobalt chromite, copper chromite, zinc titanate or iron chromite, either as such or in the form of the naturally occurring ore chrome ironstone.

The relative proportions of the catalyst components by weight of total catalyst material stable at 550 C. are

Chromium oxide (expressed as CI203) to Total promoters (expressed as oxide) 0.1 to 10% but less than the CI'203. Alumina Balance.

Preferred conditions, which are particularly suitable for use with the preferred chromium oxide on alumina catalyst are pressures of up to 200 p.s.i.g., including atmospheric pressure or below, and space velocities of the liquid feedstock of from 0.1 to 2.0 v./v./hr. A hydrogen-rich gas is produced in the process and may be recycled to the reaction zone although it is to be understood that the process may be carried out without such recycle or the addition of extraneous hydrogen to the reaction zone.

In the case of regenerable catalysts the process is advantageously carried out with a fluidised or moving bed of catalyst although the use of stationary beds of catalyst is also possible.

The cycle oils used as feedstock in the present invention may be derived from any catalytic cracking feedstock, for example a gas oil fraction or a wax distillate fraction. Cycle oils, particularly when wax distillate fractions are used as cat. cracker fcedstocks, may contain an appreciable quantity of olefins. They may also contain an appreciable quantity of sulphur compounds. If such unsaturated and sulphur containing cycle oils were to be solvent extracted the olefins would be partitioned between raflinate and extract and the sulphur compounds would go into the extract. When the cycle oil contains olefins and/or sulphur compounds, therefore, it is preferred to subject it to a hydrogenation treatment prior to solvent extraction. In this way olefins are hydrogenated to paraflins and sulphur compounds are decomposed, thereby increasing the yield of raflinate.

The hydrogenation treatment may use any convenient hydrogenation catalyst which should, however, be sulphur-insensitive and have desulphurising properties if the cycle oil contains sulphur. Suitable catalysts are, for example, cobalt and molybdenum oxides on alumina, molybdenum oxide on alumina, and tungsten-nickel oxides or sulphides on alumina and the preferred conditions are within the range 370-427 C., 600l500 p.s.i.g., /24 v./v./h., and 1000-4000 s.c.f./b. gas recycle. 1 to 5% wt. cobalt oxide, expressed as C00, and 5 to 25% wt., molybdenum oxide, expressed as M00 on alumina is the preferred catalyst, the term cobalt and molybdenum oxides includin either cobalt or molybdenum oxides as such, or as cobalt molybdate, or both.

When a hydrogenation treatment is given prior to solvent extraction, the extract from the solvent extraction will be a highly aromatic material with a high specific gravity, low sulphur content and low pour point. It may be used as a source of specific aromatics or in small amount, as a blending component to increase the specific gravity and lower the pour point of diesel oils.

While a hydrogenation treatment of sulphur or olefin containing feedstocks prior to solvent extraction is preferred, the present invention is not limited to this, since the extract is also a valuable product and it may not always be desirable to reduce the yield of extract and increase its aromaticity. In such circumstances it may be preferable to solvent extract the sulphur or olefin containing feedstock and then submit the extract to a hydrogenation treatment to decompose sulphur compounds and hydrogenate olefins to paraflins. The hydrogenated extract will be a high specific gravity, low sulphur content and low pour point material suitable for use in diesel oil blends.

The solvent extraction process may use any convenient solvent for example furfural, sulphur dioxide, glycols such as diand tri-ethylene glycol with or without Water, or phenol and water. The preferred solvent is furfural which may be used at 60-70" C. and a 350% treatment.

Some olefinic double bonds may have been formed during the dehydrogenation process or may have been present in the original feedstock.

The dehydrogenated material may be selectively hydrogenated to saturate olefinic double bonds without substantial hydrogenation of aromatic nuclei.

The selective hydrogenation treatment has been found to improve the colour and the odour of the product, which is particularly desirable when producing alkyl aryl compounds for detergent and wetting agent manufacture.

Suitable catalysts for the hydrogenation include nickel on a support, for example alumina (preferably 5 to 15% wt. of nickel expressed as elemental nickel), platinum or palladium on a support, for example alumina (preferably 0.1 to 5% wt. of platinum or palladium expressed as the element), cobalt and molybdenum oxides on a support, for example, alumina (preferably 1 to 5% Wt. cobalt oxide, expressed as C and to 25% wt, molybdenum oxide, expressed as M00 or tungsten and nickel oxides or sulphides (preferably containing tungsten and nickel in the ratio of 3:1 to :1 by weight).

The catalysts are preferably used within the following ranges:

The process preferably includes a distillation step which serves to remove lower boiling and higher boiling material formed during the dehydrogenation process. Such material is particularly undesirable in alkyl aryl fractions for detergent and wetting agent manufacture. In practice a cut boiling within the range 260 C. to 410 C. will contain the hydrocarbons with the required number of carbon atoms per molecule. The distillation is preferably carried out under vacuum and may be given either before or after the selective hydrogenation, if such a treatment is given.

The alkyl aryl compounds produced in accordance with the invention may be sulphonated and neutralised in known manner to produce alkyl aryl sulphonates suitable for use in the production of detergents and wetting agents. When the alkyl aryl compounds are produced from alkyl naphthenes having predominantly straight alkyl chains, the resulting detergents and wetting agents are biologically soft i.e. they have low resistance to biological breakdown.

The alkyl aryl compounds may be concentrated prior to sulphonation by subjecting the dehydrogenation reaction mixture, after selective hydrogenation and distillation if such steps are used, to an aromatic extraction process using for example solvents such as diethylene glycol, furfural or a sulphur dioxide/benzole mixture or adsorbents such as silica gel. Alternatively the sulphonation may be carried out on the reaction mixture and nonsulphonated oil separated and preferably recycled to the reaction stage. This latter method in which the aromatic extraction step is omitted may be particularly suitable for use when a previous selective hydrogenation step has been given, since the likelihood of the sulphonation of compounds other than alkyl aryl compounds is minimised.

The invention is illustrated by the following example. A cycle oil obtained from the catalytic cracking of a Wax distillate fraction of a Middle East crude oil had an ASTM boiling range of 290 C.467 C. and a specific gravity (60 F./60 F.) of 0.932. This oil was solvent extracted in a stirred column using furfural as solvent, under the following conditions:

Temperature gradient C. (top)60 C. (bottom). Solventzoil ratio 3.5:1. Stirrer speed 650 r.p.rn.

The rafiinate from the solvent extraction which was obtained in 45.9% wt. yield was dehydrogcnated using a catalyst of 10% wt. chromium oxide (expressed as Cr O on alumina promoted with 1% Wt. lanthanon oxide (expressed as C0 0 and 1% wt. potassium oxide under the following conditions:

Temperature C 427 Pressure p.s.i.g 100 Space velocity v./v./hr 0.25 Recycle gas None We claim:

1. A process for production of alkyl aryl hydrocarbons from a feedstock consisting predominantly of alkyl naphthenes having from 14 to 26 carbon atoms per molecule, said feedstock obtained as a raffinate stream which boils at a temperature above 275 C. from the selective solvent extraction of a cycle oil, said process comprising, contacting the said feedstock :with a dehydrogenation catalyst at a temperature of from 370 C. to 5 C., at a pressure of up to 200 p.s.i.g., and a space velocity of from 0.1 to 2.0 v./v./hr., said catalyst comprising from 5% to 25% -Wt. of chromium oxide, expressed as Cr O supported on alumina, said process carried out in the absence of additional hydrogen.

2. A process according to claim 1 wherein olefinic double bonds in the alkyl aryl hydrocarbons produced are selectively hydrogenated without substantial hydrogenation of the aromatic nuclei.

References Cited in the file of this patent UNITED STATES PATENTS 2,380,853 Linn et al. July 31, 1945 2,471,922 Axe et a1. May 31, 1949 2,754,345 Kirshenbaum July 10, 1956 2,765,264 Pasik Oct. 2, 1956 2,920,115 Friedman Ian. 5, 1960 

1. A PROCESS FOR PRODUCTION OF ALKYL ARYL HYDROCARBONS FROM A FEEDSTOCK CONSISTING PREDOMINATLY OF ALKYL NAPHTHENES HAVING FROM 14 TO 26 CARBON ATOMS PER MOLECULE, SAID FEEDSTOCK OBTAINED AS A RAFFINATE STREAM WHICH BOILS AT A TEMPERATURE ABOVE 275*C. FROM THE SELECTIVE SOLVENT EXTRACTION OF A CYCLE OIL, SAID PROCESS COMPRISING, CONTACTING THE SAID FEEDSTOCK WITH A DEHYDROGENATION CATALYST AT A TEMPERATURE OF FROM 370*C. TO 580*C., AT A PRESSURE OF UP TO 200 P.S.I.G., AND A SPACE VELOCITY OF FROM 0.1 TO 2.0 V./V./HR., SAID CATALYST COMPRISING FROM 5% TO 25% WT. OF CHROMIUM OXIDE, EXPRESSED AS CR2O3, SUPPORTED ON ALUMINA, SAID PROCESS CARRIED OUT IN THE ABSENCE OF ADDITIONAL HYDROGEN. 